Intervertebral disc cell response to dynamic compression is age and frequency dependent

Authors

  • Casey L. Korecki,

    1. Spine Bioengineering Lab, College of Engineering and Mathematical Sciences, University of Vermont, Burlington, Vermont 05405
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  • Catherine K. Kuo,

    1. Cartilage Biology and Orthopaedics Branch, National Institute of Arthritis, and Musculoskeletal and Skin Diseases, National Institutes of Health, Department of Health and Human Services, Bethesda, Maryland 20892
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  • Rocky S. Tuan,

    1. Cartilage Biology and Orthopaedics Branch, National Institute of Arthritis, and Musculoskeletal and Skin Diseases, National Institutes of Health, Department of Health and Human Services, Bethesda, Maryland 20892
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  • James C. Iatridis

    Corresponding author
    1. Spine Bioengineering Lab, College of Engineering and Mathematical Sciences, University of Vermont, Burlington, Vermont 05405
    • Spine Bioengineering Lab, College of Engineering and Mathematical Sciences, University of Vermont, Burlington, Vermont 05405 .Telephone: 802-656-2774; Fax: 802-656-1929.
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  • This article is a US Government work and, as such, is in the public domain in the United States of America.

Abstract

The maintenance of the intervertebral disc extracellular matrix is regulated by mechanical loading, nutrition, and the accumulation of matrix proteins and cytokines that are affected by both aging and degeneration. Evidence suggests that cellular aging may lead to alterations in the quantity and quality of extracellular matrix produced. The aims of this study were to examine the role of loading and maturation (a subset of aging), and the interaction between these two factors in intervertebral disc cell gene expression and biosynthesis in a controlled 3D culture environment. Cells were isolated from young (4–6 months) and mature (18–24 months) bovine caudal annulus fibrosus and nucleus pulposus tissue. Isolated cells were seeded into alginate and dynamically compressed for 7 days at either 0.1, 1, or 3 Hz or maintained as a free-swelling control. After 7 days, DNA and sulfated glycosaminoglycan contents were analyzed along with real time, quantitative reverse transcription-polymerase chain reaction analysis for collagen types I and II, aggrecan, and matrix metalloproteinase-3 gene expression. Results suggest that maturation plays an important role in intervertebral disc homeostasis and influences the cell response to mechanical loading. While isolated intervertebral disc cells responded to mechanical compression in 3D culture, the effect of loading frequency was minimal. Altered cellular phenotype and biosynthesis rates appear to be an attribute of the cell maturation process, potentially independent of changes in cellular microenvironment associated with lost nutrition and disc degeneration. Mature cells may have a decreased capacity to create or retain extracellular matrix components in response to mechanical loading compared to young cells. © 2008 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 27: 800–806, 2009

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